Apparatus for controlling the fuel feed in internal combustion engines



Sept. 6; 1938. e. wUNscH ET AL 2,129,613 APPARATUS FOR CONTROLLING THE FUEL FEED IN INTERNAL COMBUSTION ENGINES Filed Sept. 25. 1935 Patented Sept. 6, 1938 'ATENT OFFiC APPARATUS FOR CONTROLLING THE FUEL FEED IN GINES' INTERNAL COMBUSTION EN- Guido Wiinsch, Berlin-Steglitz,and Willy Gerisch,

Berlin-Friedman, Germany, assignors to kania-Werke A. G. vormals Centralwerkstatt- Dessau und Carl Bamberg-Friedenau, a corporation of Germany Application September 25, 1935, Serial No. 42,616

- In Germany September 27, 1934 6 Claims.

This invention relates to apparatus for controlling or adjusting the fuel feed in internal combustion engines more particularly those for use in aircraft, and in which the fuel feed is controlled or adjusted in accordance with the density of the combustion ,air.

For controlling oradjusting the fuel feed in accordance with the pressure or density of the combustion air means responsive to pressure or density variations is used.

As the controlling force or impulse generated by such means is relatively weak, it is preferable to effect such control through the medium of power operated means for amplifying the controlling impulse. Power operated means for this purpose are known. as relay and servo-motor mechanisms. Preferably also the servo-motor will exert a restoring impulse on the controlling relay as will be more fully explained hereinafter, thereby also increasing the stability of the device.

As the impulse imparted by a pressure or density responsive device is not a linear function of changes in density of the air, while, on the other hand, the fuel feed normally increases linearly with the path or stroke of the means controlling the quantity of fuel fed to the engine, it is therefore one object of this invention to provide a linear or other desired relation between the changes in density and fuel feed by modifying the restoring action exerted on the controlling relay by the servo-motor.

When a bellows or Sylphon, inclosing a, charge of gas, is used, for instancefor detecting changes in air density, the expansion path or stroke of the vessel will stand in a hyperbolic relation to changes in air density, arising from the fact that the inclosed charge of gas expands to a volume reciprocal or hyperbolic to the air density, providing the temperature remains constant. The usual construction of such vessels permitting an expansion in one direction only (for instance the longitudinal axis of a Sylphon), the

stroke thus becomes a linear function of the in- I closed volume and thereby a hyperbolic function of the air density.

If therefore the restoringaction of the servomotor is made to vary in a hyperbolic ratio in dependenceon the position of the piston of the servo-motor (each position of said.piston naturally corresponding to a corresponding density or to a definite stroke of the means responsive to changes in atmospheric density) it will be apparent that a linear ratio between theatmospheric density and the position of said piston will be obtained.

A further object of this invention is'to modify the restoring action so, as to insure a relation between the'fuel feed and the density of the combustion air as will correspond to the most favorable combustion condition, thereby preventing undue heating of the engine due to too thin a gas mixture.

side elevation largely diagrammatic of an illustrative embodiment of the invention.

In the figure a device responsive to variations in air density or pressure is shown generally at i. Said device will preferably be provided in, or connected to, the air intake passage or chamber of the engine and herein illustratively comprises a bellows 2, or Sylphon, which may be of any suitable construction. Herein said diaphragm preferably comprises a plurality of superposed plates. In the illustrative embodiment of the invention, the power operated means which actuates the means controlling the'supply of fuel to the engine conveniently consists of a servomotor operated by suitable power preferably by pressure fluid and comprises a cylinder II in which works a piston l1. Pressure fluid is supplied to said cylinder at opposite ends of said piston through passages I8 and I9 respectively which are controlled by a suitable relay operated by said means which is responsive to changes on the atmospheric pressure.

In the illustrative embodiment of the invention herein shown said relay conveniently comprises a slide valve gear l4 and valve casing M,

more times its volume withoutdanger of the stroke of. the diaphragm being opposed or hindered by spring action or resiliency of the latter.

The free end of said rod 4 abuts against an arm of an angle lever 6 adapted to rock about a fixed pivot 5, the forked free end of the other arm of said angle lever engaging a movable fulcrum I of a lever 8 at one end of the latter, said lever being pivotally connected to said valve gear M at iii. The other end of said lever forms another fulcrum 9 which is adapted to engage a movable member of suitable means to exert a restoring or return movement upon said valve gear [4, said means herein comprising a cam surface of hyperbolic ,or other surface 9'. The cam member I2 is showh as composed of a plurality of superimposed iaminations or plates l2, 12" provided with slots (not shown) extending parallel tothe plane of. the figure and through which extends the rod 2|. Clamping nuts 23, 23, having screw threaded engagement with said rod at opposite ends of the series of plates i2,

serve adjustably to clamp said plates l2 firmly together upon said rod 2|. By loosening said nuts 23, 23', said plates i2, i2" i2 maybe relatively adjusted parallel to their planes to vary the outline of the cam surface. The cam member I2 is rigidly connected to the piston rodl0 of the piston I I of said servo-motor II by rods 2| and 22, said cam member being guided for movement with and parallel to said piston by said rod 2| which slides in a suitable guide member 2!.

Said piston rod I 0 will be connected in any suitable manner to the means serving to control the fuel feed to the engine.

' For this purpose there is shown in the illustrating example a by-pass valve 25 controlling the by-pass 26 of a pump 21 supplying fuel from a tank 28 to the engine. Obviously, by opening the by-pass the amount of fuel fed to the engine will be diminished.

A compression spring 6' will preferably be provided to maintain contact between the free end of said rod 4 and the arm of said lever 6. Said spring bears with one end against a fixed part la of the apparatus and with its other end against the arm 81: of said lever 6.

From the above it will be apparent that should the pressure or density of the air in the air supply passage or chamber diminish, for example, thus causing said diaphragm to expand, rod 4 will turn angle lever 6 clockwise about its pivot 5, thereby swinging lever B contraclockwise about its fulcrum 9 and moving valve gear I to the left. Passage IE .will thus be uncovered and pressure oil will flow from the valve casing I! through said passage into the chamber below the piston H and will cause the latter to rise. Oil above the piston will escape through passage is, also uncovered by said valve gear, and out through a discharge passage 20.

Said upward movement or stroke of said piston ll effects a corresponding movement of said cam surface. A hyperbolic cam will therefore restore the valve ,to a neutral position by a displacement of the lever pivot 9 which is a hyperbolic value of the piston stroke. As the controlling movement of the bellows 2 and correspondingly the pivot .7 was a hyperbolic function of the change in density, the result is a movement of the piston which is a linear function of the change in density. It follows that the quantity of fuel fed to the engine will be diminished in response to the density of the air.

richer mixture that will develop less heat in burning.

On the other hand there are certain engines which require that the normally constant fuel to air ratio by weight shall be varied in favor of the fuel in the case of lower air densities In practice it is found that for almost every type of engine there exists a definite curve or graph of the most favorable fuel consumption.

Another object of the present invention is therefore to vary the restoring action or return movement of the servo-motor in dependence upon the position of the piston of the latter in a ratio determined by the curve or graph of the most favorable fuel consumption, or otherwise stated, to vary the restoring action of the fuel control in dependence upon the state from time to time of the fuel feed controlling action in a ratio determined by the most favorable fuel consumption. This result may be conveniently obtained by adjusting the cam surface l2 so that the path or stroke of the piston rod III, that is to say the variation in the fuel feed dependent upon said stroke,shall stand in a ratio to the changes in atmospheric density determined by the fuel consumption curve or graph. It is thus possible by adjusting or exchanging the restoring cams to adjust one standard regulating device to engines of different fuel consumption characteristics.

We are aware that our invention may be emclaims rather than to the foregoing description to indicate the scope of the invention.

We claim:

1. Apparatus for controlling the fuel feed of internal combustion engines, more particularly for aircraft,comprising, in combination, a servomotor connected to control the fuel feed; a relay connected to actuate said servo-motor; means responsive to variations in combustion-air density and connected to exert a controlling action on said relay which is a predeterminable function of the air density; and means responsive to movements of said motor and connected to exert a restoring action on said relay which is an iden-, tical function of the servo-motor movement,

whereby the servo-motor movements become dilows being connected to exert a controlling impulse on said relay which is substantially a hyperbolic function of the air density; and means responsive to movements of said servo-motor and connected to exert a restoring impulse on said relay which is also substantially a hyperbolic function of the servo-motor movement, whereby portional to variations in density.

3. Apparatuslior controlling the fuel feed of internal combustion engines, more particularly for aircraft comprising, in combination, a pressure fluid operated servo-motor connected to control the fuel feed; a valve connected to control the new of operating fluid for the motor; a bellows inclosing a charge of gas and responsive to variations in density of the combustion air, said bellows being connected to exert a controlling impulse on said valve which is substantially a hyperbolic function the air density; and a cam actuated by the servo-motor and being so shaped as to exert a restoring impulse on said valve which is substantially a hyperbolic function oi the servo-motor movement, whereby the servo-motor movements become directly proportional to variations in density.

4. Apparatus for controlling the fuel feed of internal combustion engines, more particularly for aircrait, comprising, in combination, a servomotorconnected to control the fuel feed; a relay connected to actuate said servo-motor means responsive to variations in combustion-air density and connected to exert acontrolling action on for aircraft, comprising in combination, a servomotor connected to control the fuel feed; a relay connected to actuate said servo-motor;-a bellows inclosing a charge otgas and responsive to varia-- tions in density oi the combustion air, said bellows being connected to exert a controlling impulse on said relay; a cam actuated by the movements oi the servo-motor and connected to exert a restoring impulse on said relay, said cam being so shaped as to restore said relay to its neutral position upon the servo-motor reaching the most favorable fuel teed condition, which is predeterminable for each engine as a function of the combustion air density, respectively 01' the controlling impulse created by the bellows.

6. Apparatus for controlling the fuel iced of internal combustion engines, more particularly for aircraft, comprising, in combination, a pressure fluid operated servo-motor connected to control the fuel feed; a valve connected to control the now of operating fluid for the motor; a bellows incloslng a'charge of gas and responsive to variations in density of the combustion air; said;

bellows being connected to exert a. controlling impulse on said valve which is a predeterminable iunction of the air density; and a cam actuated by the servo-motor and connected to exert a restoring action on the said valve, said cam being so shaped as to restore the valve to its neutral 

